Digit indicator glow-discharge lamp



June 8, 1965 1'. P. J. BOTDEN DIGIT INDICATOR GLOW-DISCHARGE LAMP Filed June 8, 1961 IN VEN TOR.

TI-EODOOR E J. BOTDEN BY I i AGENT FIG.2

&188510 DEGHT INDECATUR GLUW DSCEARGE LAMP Theodoor Peter Johannes Eotden, Eindhoven, Nether lands, aesignor to North American Philips Company,

Inat, New York, Nfi., a corporation of Deiaware Filed `inne 8, 1961, Ser. No. 115307 Claims priority, application Netherlands, July 15, 1969, %3,875 1 Claim. (CI. 3213-1695) The invention relates to a digit indicator glow-discharge lamp in which the cathode consists of a number of digits arranged behind each other in prallel planes, which digits are arranged between grid-shaped anodes and in which an auxilary anode is provided in the proxinity of each digit so that, when a voltage is applied between the parallel connected anodes and the parallel connected digits, the discharge is produced towards the digit the associated auxiliary anode of which has a low positive Voltage with I respect to the anodes.

In a construction described in US. Patent 3,075,l19, the cathodes and the anodes are stacked along two in sulating supporting rods by means of perforated tags, insulatng rings ensuring the correct distances. The auxiliary anodes consist of substantially the same windows as the anodes; however, only a few Wires are stretched on the former. It is objectionable that for each digit three electrodes of a substantially equal size must be spaced apart by accurately determined distances, which renders the requirements of the mourting severe.

The inventon has for its objectto provide a structure which is Simpler and consequently cheaper than that described in the patent.

In a glow-discharge indicator lamp of the type described in the patent, according to the invention, the auxiliary anodes consist of metal rings which are slipped onto the insulating supporting rods and the diameters of which are at the most twice those of the insulatirg rings which separate the auxil-iary anodes and the cathode digits.

Owing to the small dimensions of the auxiliary anodes, the distances from the cathodes are accurately determined by the interposed insulating rings, whereas in contradistinction to the Construction described in the patent, the sagging of the auxiliary anodes and cathodes does not have any influence on these distances.

The auxiliary anodes located on the two supporting rods, and associated with one cathode, may be connected in parallel, but it is sufficient to use only one of the two, or it is even possible to replace one of the two by an insulating ring.

The invention will now be described more tully with reference to the accompanying drawing in which:

FIG. 1 is a developed perspective view of a glow- Patented .inne 8, 1965 discharge lamp according to the invention, but in which only a few of the electrodes are shown for the sake of clarity, and in which the distances are enlarged, and

FIG. 2 is a sectional view of the axis of the lamp.

In FIG. 1, besides a plurality of supply pins 20, two supporting rods 13 are included in the bottom of the lamp 15, which rods are coated with a layer of enamel 14. Eleven grid-shaped anodes 12 are slipped around the supporting rods, between which anodes are interposed the digits 0-9, of which, however, only three are shown, namely 1-5-9, indicated by 1, 5 and 9. The digits are separated from the anode located at the bottom by insulating rings 317. Separated from the digits by insulating rings 18, on the supporting rods there are also arranged ring-shaped auxiliary anodes HO to H9, of which only Hi and HEE are shown. The auxiliary anodes are separated from the associated anodes by insulating p rings 19. The width of the anodes is about 22 mm., the

thickness of the anode grids is about 0.3 mm. and the wires of which have 40 microns in diameter, The insulating rings 17, 18 and 19 have thicknesses of 0.8, 0.2 and 0.5 mm., respectively. The thickness of the digits is 0.13 mm. and that of the auxliary anodes 0.1 mm. The auxiliary anodes have a diameter of 5 mm. and the insulating rings 17, 18 and 19 have a diameter of 3 mm. The head of the bulb of the lamp is designated by 16.

In FIG. 2, all parts are shown in section,

What is claimed is:

An indicating tube of the glow-lamp type comprising an envelope having a transparent viewing portion, and within the envelope an onizable medium, a pair of insulating support rods, and mounted on said support rodl in viewable position a plurality of character-like cathodes` positioned in parallel planes, a grid-like anode positioned i between each pair of successivo cathodes, and an annular metal member adjacent to and separated from each Cathode by an insulating member having a given diameter, said annular member constituting an auxiliaryanode, said auxiliary anode being spaced from an adjacent cathode a distance at which with a small positive potential applied thereto relative to the anode a discharge is initiated between the cathode and anode associated therewith, said annular metal member having a diameter not exceeding twice the diameter of the`annular insulating member,

and means to connect the cathodes and the anodes, respectively, in parallel.

References Cited by the Examiner UNITED STATES PATENTS 2,990,061 6/61 McCauley 313-1095 GEORGE N. WESTBY, Pr'mary Exam'ner. 

